Polyetherimides (“PEIs”) are amorphous, transparent, high performance polymers having a glass transition temperature (“Tg”) of greater than 180° C. Polyetherimides further have high strength, heat resistance, and modulus, and broad chemical resistance, and so are widely used in applications as diverse as automotive, telecommunication, aerospace, electrical/electronics, transportation, and healthcare. Polyetherimides can be manufactured by polycondensation of a dianhydride with an organic diamine (polycondensation).
An ongoing challenge associated with the use of polyetherimides is achieving low color polyetherimide, specifically polyetherimides having a low yellowness index. Lower color polymers have a wider range of commercial uses, for example, including optical applications. Use of lower color polymers also makes it easier to perform color matching applications. Furthermore, many customers prefer lower color polymers, because it enables them to make more transparent parts and develop a wide array of products that meet customer expectations.
Accordingly, there remains a continuing need in the art for a method to reduce the color (e.g., yellowness) of polyetherimides in order to meet the product demands of many applications.